The present invention pertains to a motor vehicle seat with longitudinal upper and lower adjustment tracks.
In the case of a known motor vehicle seat of this type, see for example, EP 0 265 747 B 1, the seatbelt buckle mounting is embodied as two pieces, so that the part that is connected with the upper track of the seat""s longitudinal adjustment device is surrounded by a closed longitudinal guide of the other part. The longitudinal guide permits the shifting of both parts towards each other when the motor vehicle seat is adjusted in elevation or inclination. In the event of a crash, however, both parts must be pivoted towards each other so that a catch projection on one part engages the catch toothing of the other part. Pivoting is possible only if the longitudinal guide is destroyed.
The amount of the pivoting torque, which expands or shears off the longitudinal guide and causes the catch projection to engage the catch toothing, is difficult to determine in advance and to maintain accurately during manufacturing. Premature engagement of the catch toothing must be avoided at all costs, because with each engagement, the seatbelt mounting becomes unusable. In addition, the effective duration of the forces that are necessary to expand or shear off the longitudinal guide can delay the catching process.
Taking this state of the art as a point of departure, the main purpose of the invention is to improve the seatbelt buckle mounting on known types of motor vehicle seats, so that when used, the mounting is not destroyed and is effective in the presence of a defined triggering force.
This task is accomplished with the longitudinal adjustment device including the guiding surface provided on only one side of the first part of the seat buckle mounting and the opposing surface of the second part, which works in concert with it, is held by means of a spring in contact with the guiding surface until the load limit of the seatbelt buckle mounting is reached and when the load limit that is determined by the retentive force of the spring is exceeded, the opposing surface is lifted from the guiding surface and the catch projection of the second part pivots into the catch toothing of the first part.
The spring permits a precise calculation of the retentive force at which the catching of the seat belt mounting occurs. When catching occurs, no structural elements are damaged or destroyed; therefore, catching can be induced at an early stage when the motor vehicle undergoes comparatively slight decelerations. The spring prevents the seatbelt buckle from rattling when the vehicle seat is unoccupied.
In the following, two preferred embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein: